1. Field of the Invention
The invention relates to a resilient plug, particularly a rubber plug, to a fluidproof construction and to a connector.
2. Description of the Related Art
U.S. Pat. No. 6,764,329 discloses a rubber plug to be mounted on a wire connected with a terminal fitting and inserted into a cavity of a connector housing. Outer lips are formed on the outer circumferential surface of the rubber plug and closely contact the inner circumferential surface of the cavity while being resiliently deformed. Inner lips are formed on the inner circumferential surface of the rubber plug and closely contact the outer circumferential surface of the wire while being resiliently deformed.
The rubber plug is formed so that the inner and outer lips are displaced in a longitudinal direction to reduce frictional resistance when the rubber plug is inserted. Thus, no inner lips are present in areas of the inner circumferential surface aligned with the outer lips. The outer lips may displace to escape toward an inner circumferential side with a reaction force acting on the outer lips from the inner circumferential surface of the cavity. Therefore sealing between the outer lips and the inner circumferential surface of the cavity may become unstable.
Japanese Unexamined Patent Publication No. 2006-147421 discloses a conventional waterproof construction for a wire end. The wire has a conductor made of a twisted strands surrounded by an insulating coating. A cylindrical rubber plug is mounted on an end portion of the wire and held in close contact with the outer circumferential surface of the wire. The rubber plug is inserted together with the wire into a cavity formed in a housing, and the outer circumferential surface of the plug is held resiliently in close contact with the inner circumferential surface of the cavity.
The thickness of the insulating coating may be reduced if the wire is exposed to a high or low temperature environment. Thus, a difference between the minimum inner diameter of the rubber plug and the outer diameter of the wire increases and compressive stress acting on the inner circumferential surface of the wire decreases. As a result, a waterproof property between the wire and the rubber plug may be impaired.
On the other hand, a squeeze margin of the rubber plug against the wire could be set larger to ensure the waterproof property. Thus, insertion resistance upon inserting the wire into the rubber plug becomes excessive, thereby reducing assembling efficiency.
The invention was developed in view of the above situation and an object thereof is to obtain an appropriate sealing property.